package com.xxx.util;

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * MD5加密工具类
 * 
 * 
 * 
 */
public class MD5Util {

	private static final Logger logger = LoggerFactory.getLogger(MD5Util.class);
	
	private static final String MD5_SALT = "xxx";
	 
    /**
     * 32位加密
     * 
     * @param s
     * @return
     */
    public static final String MD5_32(String s) {
    	s = s + MD5_SALT;
    	String result = null;
        char[] hexDigits = {
                '0', '1', '2',  '3',  '4',  '5',  '6',  '7',  '8',  '9',
                'a',  'b',  'c', 'd',  'e', 'f'
        };
        try {
            byte[] btInput = s.getBytes();
            // 获得MD5摘要算法的 MessageDigest 对象
            MessageDigest mdInst = MessageDigest.getInstance("MD5");
            // 使用指定的字节更新摘要
            mdInst.update(btInput);
            // 获得密文
            byte[] md = mdInst.digest();
            // 把密文转换成十六进制的字符串形式
            int j = md.length;
            char[] str = new char[j * 2];
            int k = 0;
            for (int i = 0; i < j; i++) {
                byte byte0 = md[i];
                str[k++] = hexDigits[byte0 >>> 4 & 0xf];
                str[k++] = hexDigits[byte0 & 0xf];
            }
            result = new String(str);
        } catch (Exception e) {
        	logger.error(e.getMessage(), e);
        }
        return result;
    }

    /**
     * 16位加密
     * 
     * @param s
     * @return
     */
    public static final String MD5_16(String s) {
    	s = s + MD5_SALT;
        String result = null;
        try {
            MessageDigest md = MessageDigest.getInstance("MD5");
            md.update(s.getBytes());
            byte[] b = md.digest();
            int i;
            StringBuilder buf = new StringBuilder("");
            for (int offset = 0; offset < b.length; offset++) {
                i = b[offset];
                if (i < 0)
                    i += 256;
                if (i < 16)
                    buf.append("0");
                buf.append(Integer.toHexString(i));
            }
            result = buf.toString().substring(8, 24);
        } catch (NoSuchAlgorithmException e) {
        	logger.error(e.getMessage(), e);
        }
        return result;
    }

    public static void main(String[] args) {
        System.out.println(MD5Util.MD5_32("gwq123"));
    }
}
